Needle cam for circular knitting machines



Feb. 3, 1948. H. L. CURTIS ET AL NEEDLE CAM FOR CIRCULAR KNITTING MACHINES Filed March 29, 1946 3 Sheets-Sheet 1 Y E l R L 5 Wm? m l 0 MM 1w M HH NT 6 EEE r MW wmmma Q mm W 66 2 il il 1| PH W 1/ Lil In x m m A m M n m N W E k Feb. 3, 194 s.

' H. L CURTIS ET AL NEEDLE CAM FOR CIRCULAR KNITTING MACHINES Filed March 29, 1946 '3 Sheets-Sheet 2 RGE H.

their Feb. s, 1948.

H. L. CURTIS ET AL NEEDLE CAM FOR CIRCULAR KNITTING MACHINES 3 Sheets-Sheet 3 Filed March 29,, 1946 lizfuenivrs HORACE L. CURTIS GEORGE H. MCKINLEY.

GEORGE H. MILLER by f'heir miter-weys MMM Patented Feb. 3, 1948 NEEDLE CAM FOR CIRCULAR KNITTING MACHINES Horace L. Curtis, Gilford, and George H. McKinley and George H. Miller, Laconia, N. IL, assignors to Scott & Williams, Incorporated, Laconia, N. H., a corporation of Massachusetts Application March 29, 1946, Serial No. 658,082

14 Claims.

This invention relates to circular knitting machines of the independent latch needle type, and more particularly to means for eliminating the variations in size of the stitches in hosiery fabric, known as streaks.

In circular knitting machines using independent latch needles, and particularly in machines making fine-gauge hosiery fabrics at high, speed, fabric is frequently produced which has a fault known as streaks. These streaks take the form of an enlargement or reduction in size of the loops in a plurality of adjacent wales and courses. This fault presents a visible imperfection when the stocking is observed against a contrasting background. It has been suggested heretofore that these streaks are due to the needles driving or flirting down when passing under the stitch cam. When there is driving, the needles go further down than is necessary to pass under the point of the stitch cam, longer stiches are made and streaks result. While these imperfections may be due to many factors which may or may not all be present in any particular machine, by long research we have found that the novel needle control hereinafter described has a marked effect in eliminating streaks.

In the drawings:

Figure 1 is a view in elevation of a stitch cam, end cam and associated needle butt of a circular knitting machine, shaped and arranged in accordance with our invention, the part with the arrow indicating the direction of needle movement being the run-down side of the stitch cam in elevation;

Figure 2 is a development of the cams of Fig. I viewed from the outside of the machine, the needles moving from left to right, as shown by the arrows;

Figure 3 is a view in elevation of the stitch and end cams of Figs. 1 and 2 as they appear from the center of the knitting machine, the few needles shown on the run-down side of the cam having their shanks dotted in to permit a clearer view of the stitch cam;

Figure 4 is a view in elevation of the run-down face of the stitch cam of Figs. 1 and 2;

Figure 5 is a view in vertical longitudinal section through the central portion of the stitch cam of Figs. 1 to 4, looking from the outside of the machine, showing the bevel at the point, the view being taken on the line 5-5 and in the direction of the arrows of Fig. 4;

Figure 6 is a view similar to Fig. 5 of a stitch cam in which the bevel at the point is slightly rounded circumferentially of the machine;

10 near the stitch point, which point is indicated by the short, heavy arrow at the top of the figure; while Figure 11 is a much enlarged viewin elevation showing the dimensions of the needle butts and 15 their path at the stitch point as they occur in a machine made in accordance with our invention.

Streaks in knitted fabrics have been known for many years, have always been a source of trouble to the industry, and much eiiort has been expended in trying to eliminate them.

Since stitch length is involved, it has heretofore been attempted to eliminate all variations in the level to which the needles are drawn down at the stitch cam by providing a completely enclosed path of travel for the needle butts. This has not been successful in eliminating streaks, for several reasons. In the first place, regardless of uniformity of dimensions of needle butts, the more .one seeks to confine the needle butts, top

and bottom, at all times, the more friction there is on the needle and the more likely the needle is to jump or twist out of position at the first opportunity. Thus the toe of a butt can get ahead or behind the shank of the needle even in an enclosed path, and cause trouble. In the second place, needle butts have not been of identical dimensions and the clearances needed to avoid jamming the needles are such that variations in needle movement can occur in the enclosed path which may cause streaks. We have even found that the complete enclosure of the needle butts makes these clearances a real cause of trouble.

Our novel means of control of the needles is 5 as follows. In the first place, we have provided an extraordinarily close and novel control of the needle butts at the vital point in the needle path, and relieve the butts at other points. In the second. place, we keep the vertical dimension of the needle butts from one side to the other within certain numerical limits in correlation with our novel control. These features combine to give absolutely uniform action of the needle shanks at the vital point and to minimize and make ineffective am forces tending to cause nee 3 dles to drive down beyond the point of the stitch cam or otherwise cause variation at the critical point.

As part of this cooperative combination, we provide a land or flat of a certain character in the bottom. or end cam underneath the stitch cam. The function of this end cam is to raise the needles after they have been drawn down by the stitch cam. The surface of the cam therefore slopes generally up. The particular fiat we use is a horizontal land which begins a reasonable distance prior to the point of the stitch cam and extends past that point a distance 4 structed, the needles N lie in vertical slots in the needle cylinder (not shown) with their shanks 29 in the slots and their butts n n projecting from the cylinder. While in the drawings we have indicated only a normal short butt n and a normal longbutt n it will be understood that needles with various lengths of butts are commonly used. The butts shown may be considered the normal short and long ones, for the purposes of explanation. In Fig. 1 we have indicated. the type of needle which forms the subject-matter of the Harry Swinglehurst Patent No. 2,010,205, dated August 6, 1936, but it should which we have found must be carefully controlled. It should in no case be more than the thickness of a butt of a needle, and preferably is slightly less. For example, if the thickness of a needle butt is say .0132 of an inch, we have found that a most efficient distance for the land or flat to extend beyond the point of the stitch cam is about .010 of an inch. We find this apparently impossible dimension works most effectively for our purposes, in spite of the fact that the vertical distance between the point of the stitch cam and the flat is only enough for a slip" fit of a needle butt. By slip fit we mean one in which there is no appreciable movement in the direction of the fit.

In the drawings we have shown two embodiments of our invention which differ in the exact shape of the stitch cam. We will first describe the form shown in Figs. 1 to 5 and 7 to 11, and then the modification of Fig. 6. The invention, of course, is concerned more particularly with the manufacture of ladies. hosiery where fine gauges and fine yarns are found. Where in this specification reference is had to fine-gauge machines, it should be understood that reference is had to one wherein 30 or more needles per inch are present in the needle cylinder. For example, a machine having 400 needles in a 3 /4" diameter would be known as a fine-gauge machine. Such a machine has about 34.53 needles per inch. It should be understood, of course, that in the drawings, for the sake of clarity, the spacing and gauge of the needles do not follow exactly the scale and gauge found in the actual machines.

The invention will be shown and described embodied in the well-known Scott & William independent needle circular hosiery machine having a revolving needle cylinder, butit should be understood that the invention". is applicable also to circular knitting machines for making hosiery, in which it is the cam cylinder that revolves. For reference to an example of the well-known Scott 82 Williams hosiery machines, attention is called to the patent to Robert W. Scott No. 1',-

152,850-', dated September 7, 191 5. It should be understood that this application shows the invent'ionapplied tothe machines shown in that patent and in the Robert W. Scott Patent 1,282,- 958, dated October 29, 1918, insofar as the parts of the machine are not shown in the drawings of the present application.

.In machines of'this type, as shown in the Scott Patent 1,282,958, two stitch cams are provided; the left-hand stitch cam 360for use when the machine is making round-and-round knitting, and the leading or' right-hand stitchcam 36 (not shown in the present application), for use when the machine is knitting in the reverse direction during recipro'catory knitting in mak- 'ing the heel or' toe. As theseimachines are conbe understood that needles of other types can be used, if desired. We are disregarding such special needles as the fashion mark needles.

In passing through the knitting wave, the butts 11. n of the needles ride down the rundown face 364 (Fig. 3) of the stitch cam 360 and after passing the point 2| of the cam, are led upwardly again by the side or end cam 352 which lies underneath the stitch cam 36!), ascan be seen, for example, in Fig. 2 of the drawings. Speaking generally, the length of the stitch drawn is determined by the distance that the needle is pulled down, so that the distance from the stitch point 2| of the stitch cam to the surfaces of the knocking-over ledges of the webholders or sinkers (not shown), taken in connection with the length of the needle, determines the length ofstitch, generally speaking.

It has been customary for some years in making these stitch cams to bevel ofi the run-down face of the stitch cam along its outer edge to relieve the cam. One form of such construction is shown in the patent to Robert W. Scott No. 1,311,093, dated July 22, 1919, in which half the width of the face of the cam is relieved. In the drawings of the present application the rundown face 384 has been relieved for half its width, the relief being the portion marked 22 in Figs. 1 and 2. It willbe noted that thi relief is about the same width as the remaining fiat portion on which the butts of the needles ride down the cam. It has also been customary to relieve the rising face 362 of the stitch cam in a similar manner, as shown at 23 in Figs. 2 and 7. It has also been known to relieve the upper face of the end cam 352. But in the prior art thi has been relieved only to the extent that the rundownface of. the stitch cam is shown relieved in Figs. 1 and 2. In accordance with our invention the relief of this bottom or end cam 352 is carried out to a greater extent and performs a some what different function, as will be explained after the shape of the improved stitch cam has been described.

It should be noted that in accordance with our invention the stitch cam has been relieved at the point. This is done by bevelling oi? the point of the stitch cam at the outer end as it lies in the machine, in a surface or plane which difiers from the plane of the relief onthe run-down and rising sides of the stitch cam. Specifically, in the embodiment now being described, the relief of the point of the stitch cam consists of a bevel or iiat surface 24 at the point of the cam so that the radial length of the cam at the point is less than half the efiective length of the normal short nee-. dle butt in the machine and adjacent the needle cylinder, as shown in Fig. 1. As shown, this plane preferably is not quite horizontal but slopes in a somewhat downward direction from the rundown .side of the cam to the rising side of the stitch cam. If desired, it can be given slight curves when the cam is viewed from the side, as shown at 25 in Fig, 6. This provides a smooth transition from the run-down face 364 to the ,bevel 24. The surfaces are plane, however, when viewed radially, as shown in Fig. 2.

Where in this specification we speak of height of butt. we mean the vertical distance from one edge of the butt to the other edge as the needle stands in the slot. Where we speak of length of butt we refer to the radial overall length from heel to toe. Where we speak of the effective length of a needle butt we mean the portion projecting from the needle cylinder and therefore available as working surfaces for the cams.

To show how this surface compares with the other cam surfaces, we refer to Fig. '7. This is the bottom view of the stitch cam. The arrow at the left of the figure indicates the direction in which the needles move past the cam in roundand-round knitting, and it will be seen that the fiat portion of the run-down face is reduced in width as it approaches the knocking-over point of the cam. In other words, the width of contact of the needle butts decreases sharply as the needle comes down to the stitch point. This is shown diagrammatically in Fig. 10, where, contrary to Fig. '7, the needles are moving from right to left. It will be seen that whereas a long needle butt n will have a width of contact with the rundown face 364 of the stitch cam of perhaps twice the effective length of one of the normal short needle butts n in the machine, this width becomes reduced to about half the length of the normal short butt in the machine as the needle approaches the stitch point.

The invention can be used whether or not the lower end of the run-down face of the stitch cam is hollow ground in accordance with well known practice. The drawings show the rum down face without the depression adjacent the point which constitutes this form of hollow grinding.

In these fine-gage machines where needles frequently have shanks and butts whose thickness 26 (Fig. 11) is say only .0132 of an inch, and the walls of the cylinder (not shown) are of similar thickness, the impact of the butt of a needle which has been travelling in a horizontal direction on the run-down face 36 of the stitch cam is very severe. For example, if the machine is a 3%" machine with 400 needles revolving at a rate of say 200 revolutions a minute, there are over 1300 needles a second hitting the cam. This means 80,000 needles 9. minute are travelling by the stitch cam. With such thin butts projecting from such thin needle cylinder walls, it is not surprising that the impacts set up strains in the projecting needle butts which tend to cause irregularity in movement of the needles, particularly at the point 2| of the stitch cam, For example, as indicated by dotted lines in Fig. 10, the free ends or toes 2'! of the butts may tend to be dragged backward by friction as they travel down the run-down face of the stitch cam. This may cause the toe to jum ahead of the heel at a later point. It is necessary, however, to keep the friction per square inch between the needle butt and the cam as low as possible while the needle is travellin down this surface. The bearing width is maintained for a considerable distance down the cam. However, as a, needle reaches the point of the stitch cam it becomes imperative that any such displacement of the needle butt as indicated above, or, in fact, any other displacement of the butt which has not been eliminated during the travel down the run-down face, must be handled in such a way that it does not affect the size of loop drawn. For example, in the case of a needle thus twisted, if the stitch cam point 2| is not relieved, the heel 28 of the butt, namely, the portion closest to the shank'ZB, may reach the point 2| ahead of the toe. This possibility heretofore has made it necessary to have appreciable clearances between the stitch cam and bottom or end cam. What is more important, it means that the needle will have a dwell at the level of the point of the stitch cam. Such a dwell tends to effect the amount of yarn drawn and therefore makes an irregular-size loop,

We have found that the radial length of the point 2| of the stitch cam should be less than approximately half the effective length of the normal short needle butt in the machine in order to concentrate the required pulling down of the needle near to the heel 28 of the butts of the needles, i. e., adjacent the needle cylinder. In this way the leverage of the friction of the butt on the stitch cam is kept to a minimum at the crucial point in the path of travel of the needles. This cutting down of the radial length of the stitch cam at the point of less than half the length of the normal short needle butt in the machine has the further value of practically eliminating any dwell due to contact between a lagging or leading toe of a needle butt and the point of the stitch cam. We have also found that by providing a plane or bevel 24 which is not parallel to the run down surface 364 of the stitch cam, but turned partially toward the rising slope 362 of the cam, a useful freedom and yet secondary control of the toes of the butts of the needles is provided. Such a bevel extending fanwise from the point of the stitch cam radially outward and upward gives a clearance for the toes of the butts which have either lagged 0r sprung ahead of the heel;

This clearance is greatest on a line exactly opposite the point 2| of the stitch cam, and helps to curtail such movementswhen the toe is on either side of the point. It also provides uniform guidance or control for the toe of the butt if the needle is of such a construction and conditions are such that the top and heel of the needle are bending radially outward, thereby lifting the toe of the butt upwardly.

If desired, as further safety against any injection of irregular needle movements just before the needle butts reach the point of the stitch earn, the plane or bevel 24 can be rounded slightly at the ends 25, as shown in Fig. 6'. This avoids any possibility of the toes of the needle butts finding a jumping-01f point if they are slightly outof position when passing from the run-down face to the bevel 24 or from the bevel to the rising face 362.

The primary control of the needle elevation passes from the stitch cam 360 to the left-hand end cam 352 at the point 2| of the stitch cam and it is this end cam which raises the needles; The entire upper surface or edge of this cam is preferably relieved to the same extent as'the stitch cam by being bevelled off on the radially. upward side, as shown at the oint 35. This concentrates the pressure at the desired point and avoids trouble if the needle shank tries to arch at the middle, as mentioned above. The rising slope 353 of this cam may be substantially paral-, lel to the rising slope 362 of the stitch cam, if desired, although we .prefer to makethese two surfaces slightly divergent-say about 1 /2. The" that we have obtained this result partly by having control of the needles'effected only at the points nearest the shanks of the needles. In this way the displacement of the toes of the needles can cause no trouble near the point of the stitch cam and the dimensional relations of the two cams in the neighborhood of the stitch point are so related to the dimensions, shape and structural condition of the butts of the needles in finegauge machines as to give, accurate and much improved control with improved movement of the needles in the vital area at the point of the stitch cam, as found to be essential for the elimination of streaks.

We claim: Q

1. In a circular knitting machine, a plurality of independent latch needles, operating butts on said needles, in combination with a stitch cam and an end raising cam therefor, said end cam being below the stitch cam and. having a fiat extending past the point of the stitch cam slightly less than the thickness of one needle.

2. A circular knitting machine according to claim 1 wherein the spacing of the point of the stitch cam from the fiat of the end cam is of such a dimension that the operating butts pass between the point of the stitch cam and the flat with not more than a slip fit.

3. In a circular knitting machine having a plurality of independent latch needles, operating butts on said needles and a stitch cam therefor, in combination with an end cam hating a flat underneath the stitch cam but extending in the direction of movement of the needles beyond the point of the stitch cam a distanceslightly less than the thickness of one needle, the heights of the butts being uniform within a tolerance approximating a slip fit and the distance from the point of the stitch cam to the flat in the end cam being such that the butts pass between them with only a slip fit, whereby driving down of the needles is prevented.

l. In a circular knitting machine, a plurality of independent latch needles, operating butts on said needles, in combination with a stitch cam whose run-down face has been relieved so that the radial length of the cam at the point is located adjacent to the needle cylinder and is less than one-half the efiective length of the normal short needle butt in the machine, and an end cam below the stitch cam having a flat extending past the point of the stitch cam not more than approximately the thickness of one needle whereby driving down of the needles is prevented.

5. In a circular knitting machine, a plurality of independent latch needles, operating butts on said needles, in combination with a stitch cam whose run-down face has been relieved so that the radial length of the cam at the point is located adjacent to the needle cylinder and is less than one-half the effective length of the normal short needle butt in the machine, and an end cam below the stitch cam, whereby driving down of the needles is prevented.

6. In a fine-gauge circular knitting machine, a plurality of independent latch needles; operating butts on said needles and a stitch cam therefor, in combination with an end raising cam having a flat underneath the stitch cam extending beyond the point of the stitch earn a distance slightly less than the thickness of the needle, whereby the needles are raised after passing the point of the stitch cam without any appreciable freedom of movement, and irregularities in the knitting are prevented.

'7. In a fine-gauge circular knitting'machine, a circle of independent latch needles, operating butts on said needles and a stitch cam' therefor, in combination with an end raising cam having a horizontal flat such that the operating butts pass between the point of the stitch cam and the fiat with not more than a slip fit, the fiat extending beyond the point of the stitch cam a distance slightly less than the thickness of the needle, for the purposes described.

8. In a circular knitting machine, a circle of independent latch needles, operating butts on the lower ends of. said needles, in combination with a stitch cam having a run-down face whose width of contact with theneedle butts decreases at the point of the stitch cam-to a radial width of not more than half the effective length of the normal short needle butt in the machine adjacent to the needle cylinder, and an end cam having a flat underneath the point of the stitch cam and extending beyond the point not more than the thickness of the needle butt, the butts of the needles having heights which are accurate within a tolerance of .001" and the space between the point of the stitch cam and the flat on the end cam allowing the butts of the needles to pass with a tolerance of not more than .001", whereby driving down of the needles is prevented and streaks in the resulting fabric are avoided.

9. In a knitting machine according to claim 3, the provision of relief at the flat on the end cam so that its effective width bearing on the butts of the needle is not more than half the effective length of the normal short needle butt in the machine, whereby control of the needles is effected only at points nearest to the shank of the needle and displacement of the toe of the needle butts is minimized.

10. In a circular knitting machine, a circle of independent latch needles, a revolving cylinder carrying said needles with their hooks facing radially outward, operating butts on said needles projecting outwardly from said cylinder and a stitch cam therefor whose run-down face is relieved on the edge away from the shank of the needle, in combination with an end raising cam having a flat under the stitch cam, the fiat extending beyond the point of the stitch cam a distance equal to slightly less than the thickness of one needle, the point of the stitch cam being relieved so as to leave a contact surface for the heel of the butt of not more than half the effective length of the normal short needle butt in the machine, the heights of the butts of the needles being uniform within a tolerance corresponding to a slip fit and the spacing between the point of the stitch cam and the flat on the end cam allowing passage of the butts with not more than a slip fit, whereby the radial positions of the toes of the butt of the needles are correctly maintained at the stitch point and stitches of uniform length are produced.

11. In a circular knitting machine, the combination of a plurality of independent latch needles, a needle cylinder in which said needles move in a vertical direction, operating butts and hooks on said needles facing outwardly and a stitch cam for the needles, said cam having a run-down surface presenting a width equal to at least half the effective length of the normal long operating butt except as it approaches the stitch point where the width is adjacent the needle cylinder and is not more than half the effective length of the normal short needle butt. I

12. In a circular knitting machine having a plurality-of independent latch needles, operating butts on said needles and a. stitch cam 'therefdr, the :provision of a. bevel radiating fainwiseoutweird and upward from the-point of the stitch cam at'a distance from the inner endo'f the point not more than half the effective length of the normal short needle butt in the machine, whereby all needles are relieved at th'e point bf the cam and butts which 'are'radially-ut of line will heat afieet the needle "movements.

13. In a circiilar-knitting machine according to claim 12, the pl'acin'g t fthebeveL-at'an angle sloping between the I ili'n-fldwn side "of the 'stitch 'ta'm andthe-hoiizolitdl, whereby the'ehalige of the needle butts-frdmbne suiface to theother is eased. I

14; In a circular knitting machine-according to claim 13, the placing *qi the "heifer-5b thatrit fans out o nboth sides of the-b'oizit'bf the stit'eh camffor the purposesdescribed. H

HORACE L? mm- G ORGE, E GEORGE REFERENCES 'GI-TED 

